Hiroshima marked the 73rd anniversary of the atomic bombing of the city on Aug. 6, 1945. Nagasaki will do the same on Aug. 9. These days serve as a reminder about the terrible effects of the atomic bombings that killed and injured hundreds of thousands of human beings, and the preciousness of peace.

The number of hibakusha, or people exposed to radiation caused by the atomic bombings, is declining year by year. According to the health ministry, there was 155,000 hibakusha as of March this year, and 90,000 hibakusha died during the past decade. The number of survivors directly exposed to radiation in the cities of Hiroshima, Nagasaki and their surrounding areas is now under 100,000 for the first time. Their average age is now 82 and they are aging.

Keiko Ogura, 81, who became a hibakusha when she was eight in Hiroshima, has been telling her story in English to foreign visitors. She offers her testimonies at international conferences and overseas events. "A day will come when only mementos are left. I testify everyday thinking this is the last day." She said.

As hibakusha numbers decline, education that carries on their voices becomes more important.

Japan's two atomic-bombed cities are enthusiastic about peace education. The city of Hiroshima has a 12-year-long peace education program covering elementary to high school students. The city of Nagasaki launched classes this year that focus on dialogue between hibakusha and students, not just on listening to the tales of survivors.

The importance of learning about peace is the same for children around Japan. One can feel what war is like by standing in Hiroshima or Nagasaki and listening to what hibakusha have to say.

However, according to the Hiroshima Municipal Government, the number of students visiting the city on school excursions dropped to some 320,000, less than 60 percent of the peak of the mid-1980s.

It is vital to prevent visits to those cities from becoming a onetime experience. Wars not only kill or injure people, but also destroy cities and nature, create refugees and make societies poor. Discussing how to stop war in classes is a possible way to build on those visits.

It is the responsibility of the government to make the world aware of the horrors of nuclear weapons. But the administration of Prime Minister Shinzo Abe turned its back on the Treaty on the Prohibition of Nuclear Weapons, which was adopted last year at the United Nations in New York. Tokyo did so in consideration of the position of Washington, which provides a nuclear umbrella over Japan. The administration says it is going to be a bridge between nuclear weapons states and countries without them, but no concrete results have emerged so far.

An international nongovernmental organization won the Nobel Peace Prize last year for its contribution to the passage of the nuclear weapons ban treaty. Japan will lose its leverage as the only country that suffered from atomic bombings if it cannot clear suspicions that its posture toward the elimination of nuclear weapons is moving backward.